The invention relates to a system for collecting samples and to a method for collecting a liquid sample, in particular, of a body fluid such as blood or interstitial fluid. The sample collection procedure involves the steps of creating a perforation in the skin by insertion of a lancet, such that the sample fluid emerges from the perforation, and of recovering the sample on a test element on which said sample can be analyzed in a test field.
In clinical diagnostics, examination of blood samples or of interstitial fluid permits early and reliable detection of pathological conditions and also specific and reliable monitoring of physical states. Medical diagnostics entails collecting a sample of blood or of interstitial fluid from the individual who is to be examined.
To collect the sample, the skin of the person to be examined can be punctured, for example, at the finger pad or ear lobe, with the aid of a sterile, sharp lancet, in order to obtain a few microliters of blood for analysis. This method is particularly suitable for sample analysis that is carried out directly after the sample has been collected.
In the area of home monitoring in particular, in other words, where persons without specialized medical training carry out simple analyses of blood or of interstitial fluid themselves, and particularly for diabetics taking blood samples on a regular basis, several times a day, to monitor their blood glucose concentration, lancets and associated devices (puncturing aids) are sold that allow samples to be taken with the least possible discomfort and in a reproducible manner. Such lancets and devices (puncturing aids) are the subject matter of, for example, WO-A 98/48695, U.S. Pat. No. 4,442,836, U.S. Pat. No. 5,554,166 or WO 2006/013045.
Self-monitoring of blood glucose levels is a method of diabetes control that is nowadays applied worldwide. Blood glucose monitors in the prior art comprise an analysis device into which a test element (test strip) is inserted. The test element is brought into contact with a droplet of a sample which has previously been collected by means of a puncturing aid, for example from the pad of a finger.
Samples of fluids, for example, body fluids such as blood or urine, are frequently analyzed using analysis appliances in which the sample to be analyzed is located on a test field of a test element and may react with one or more reagents in the test field before it is analyzed. Optical, in particular photometric, evaluation and electrochemical evaluation of test elements represent the most common methods for rapid determination of the concentration of analytes in samples. Analysis systems with test elements for sample analysis are generally used in the field of analysis, environmental analysis and in particular in the field of medical diagnostics. Test elements that are evaluated photometrically or electrochemically are of great value, particularly in blood glucose diagnosis from capillary blood.
There are various forms of test elements. By way of example, substantially square plates are known, which are also referred to as slides, in whose center a multilayer test field is located. Diagnostic test elements which are in the form of strips are referred to as test strips. The prior art extensively describes test elements, for example, in documents CA 2311496, U.S. Pat. No. 5,846,837, U.S. Pat. No. 6,036,919 or WO 97/02487.
Other multilayer test elements known in the prior art are analysis tapes comprising a multiplicity of test fields, which are wound up in a cassette and made available for use in an analysis appliance. Such cassettes and analysis tapes are described, for example, in documents DE 103 32 488, DE 103 43 896, EP 1 424 040, WO 2004/056269 and US 2006/0002816.
The numerous system components (lancet, puncturing aid, test element and analysis appliance) require a lot of space and involve complex handling. Systems have also been developed which have a greater degree of integration and are thus easier to handle and in which, for example, the test elements are stored in the analysis appliance and made available for the measurement. A further step in terms of miniaturization can be achieved, for example, by integrating several functions or function elements within a single analytical aid that is disposable. For example, the operating sequence can be greatly simplified by a suitable combination of the puncturing procedure and of the detection of the analyte concentration by means of a sensor on a test element.
U.S. Publication No. 2006/0155317 discloses a lancet device for generating a puncture wound in a skin surface, which device comprises an integrated test element in the form of a reference element with a lancet and a sample-collecting unit. The test element is coupled securely to a coupling mechanism of the lancet device. In a first position of the coupling mechanism, the lancet of the test element is actuated by means of a coupling rod and connecting rod, and a puncturing movement is carried out. By means of a pivoting movement, the entire coupling mechanism, together with the test element coupled securely thereon, is then moved to a second position in which an opening of a sample recovery channel of the test element lies over the puncture site in order to recover a liquid sample.
This concept known from U.S. Publication No. 2006/0155317 is relatively complex, since the combination of several vertical movements of the coupling mechanism and the required pivoting movements of the coupling mechanism (in each case with the test element coupled securely thereon), and the separate drive mechanism required for the lancet movement involve considerable outlay in terms of construction. Moreover, the concept illustrated therein can be technically expanded on only with difficulty, by means of a multiplicity of test elements (for example from a magazine) being used one after another in an automated manner.
WO 2005/107596 discloses a multiplicity of lancets arranged spaced apart from one another on a tape. According to one embodiment, the tape not only carries the lancets, but also a multiplicity of test elements, which are each assigned to one of the lancets. This is therefore a tape with a multiplicity of analytical aids which are arranged spaced apart from one another and which permit the integration of puncturing procedures and sample recovery procedures within one sample-collecting system.